Titan II and Titan I rockets

Titan II and Titan I rockets Image by mark6mauno Martin Marietta SM-68B/LGM-25C Titan II (center left) Titan II was the longest-serving ICBM (Intercontinental Ballistic Missile) in the U.S. Air Force strategic arsenal. The SM-68B, developed from the Titan I ICBM, was on operational alert from 1963-1987. For most of its nearly 25 years of operation,

Titan II was the longest-serving ICBM (Intercontinental Ballistic Missile) in the U.S. Air Force strategic arsenal. The SM-68B, developed from the Titan I ICBM, was on operational alert from 1963-1987. For most of its nearly 25 years of operation, Titan II was the largest and most powerful American nuclear-armed missile. The Titan design also enjoyed a long career as a space launch vehicle, sending satellites and manned spacecraft into earth orbit.

While the SM-68A Titan I system was becoming operational, the USAF recognized that it could be simplified and improved. Using the same manufacturing and test facilities, the SM-68B took shape as a major step forward in ICBM technology. Perhaps Titan II’s most important feature was its quick-launch capability. It could be launched in about 60 seconds from inside its underground silo (Titan I took 15 minutes and had to be elevated above ground first). This speed was crucial in responding to a preemptive nuclear attack before incoming missiles arrived.

New "hypergolic" liquid fuels made Titan II’s quick launches possible. Hypergolic fuels ignite on contact with one another, eliminating the need for an ignition system, and they can be stored at room temperature inside the missile. Partly as a result of using these new propellants, the SM-68B had fewer parts and a simpler design than the SM-68A. Also, a new silo design vented the tremendous blast of Titan II’s improved engines away from the missile, allowing in-silo launching and eliminating the need to elevate the SM-68B to ground level before launch.

Titan II’s advanced "all-inertial" guidance system made the missile less vulnerable to enemy attack. Each SM-68B carried its own self-contained guidance equipment and did not rely on ground computers. This improvement made widely dispersed bases possible, and Titan II sites were typically several miles apart, enhancing survivability during a potential nuclear strike. At the height of SM-68B operations, the USAF deployed 54 Titan IIs at three bases in Arizona, Kansas and Arkansas. Each base had two squadrons of nine missiles each. The combat crew for a single missile included two officers and two enlisted personnel, but many support troops were required to maintain the missiles, train crews, and provide security.

In 1981 the USAF undertook a missile modernization program, and Titan II ICBM operations ceased in 1987. Spare SM-68Bs were converted to space boosters and used to launch satellites. This role was not new for Titan II, since this powerful and reliable rocket had been used for many years in civil and military space programs. Titan IIs launched manned Gemini missions for NASA in the mid-1960s, and later Titans evolved into more powerful space boosters with the addition of "strap-on" solid rockets, launching some of the most important U.S. military satellites.

Entering operational service in 1962, Titan I was the United States’ first multistage ICBM (Intercontinental Ballistic Missile). Incorporating the latest design technology, Titan provided an additional nuclear deterrent to complement the U.S. Air Force’s Atlas missile. Though the SM-68A was operational for only three years, it was an important step in building the Air Force’s strategic nuclear forces.

The first American ICBM based in underground silos, Titan I gave USAF managers, contractors and missile crews valuable experience building and working in vast bunkers containing everything the missiles and crews needed for operation and survival. These early silos, however, had certain drawbacks. First, the missiles took about 15 minutes to fuel, and then had to be lifted to the surface on huge elevators for launching, which slowed their reaction time. Rapid launching was crucial to avoid possible destruction by incoming missiles, even though Titan shelters were designed to withstand nuclear blasts. Second, the missiles’ placement close together in groups of three –necessary because they shared a single ground-based radio guidance system — made them vulnerable to nuclear attack. All-inertial guidance, which does not depend on ground computers, was not yet perfected.

In its brief career, Titan I equipped six squadrons of nine missiles each, in Colorado, Idaho, California, Washington state and South Dakota. Although Titan I’s two stages gave it true intercontinental range and foreshadowed future multistage rockets, its propellants were dangerous and hard to handle. Super-chilled liquid oxygen oxidizer had to be pumped aboard the missile just before launch, and complex equipment was required to store and move this liquid. Kerosene fuel also was pumped aboard just before launch.

Titan I allowed USAF missileers to perfect techniques for efficiently operating strategic missile facilities spread across several states and requiring great coordination and skill. Still, the SM-68A was a transitional missile. Even as the USAF deployed 54 Titan Is on operational alert from 1963-1965, it prepared to deploy more advanced Titan IIs in their place. Later missiles, like Titan II, used safer fuels and more advanced guidance, but followed the SM-68A example of underground basing and multiple stages.